GPS receiver and calculation method of navigation solution thereof

A calculation method of a navigation solution, comprising:

• receiving a plurality of navigation signals from a plurality of respective satellites, including a first navigational signal from a first satellite;
• acquiring position information of each respective satellite from the received navigation signals and measuring respective pseudo-ranges, including a first pseudo-range;
• determining an abnormal state of a second navigation signal, wherein the second navigation signal is transmitted a time after the first navigation signal was transmitted and, upon determining the abnormal state, calculating a current position of the first satellite based upon first satellite position information previously stored in a memory before the abnormal state was determined;
• and
• estimating a second pseudo-range of the first satellite based upon the calculated current position of the first satellite and an estimated current location of a receiving unit,
• wherein the abnormal state of the second navigation signal is determined based on a change according to time of a pseudo-range or a carrier phase which is a measured value acquired from a navigation signal.

A GPS receiver, comprising:

• a navigation signal receiving unit receiving a first navigation signal from a first satellite, and wherein a first communication path from the first satellite to the receiving unit is unobstructed;
• a navigation signal processing unit acquiring position information of the first satellite and measuring a pseudo-range of the first satellite;
• and
• a pseudo-range estimating unit determining an abnormal state of a second navigation signal from the first satellite to the receiving unit, wherein the second navigation signal is transmitted a time after the first navigation signal was transmitted and, upon determining the abnormal state, estimating a current location of the receiving unit and calculating a current position of the first satellite based upon first satellite position information previously stored in a memory before the abnormal state was determined, and estimating a second pseudo-range of the first satellite based upon the calculated current position of the first satellite and the estimated current location of the receiving unit, and wherein the abnormal state of the second navigation signal is determined based on a signal to noise ratio of the second navigation signal, wherein the abnormal state of the second navigation signal is determined based on a change according to time of a pseudo-range or a carrier phase which is a measured value acquired from a navigation signal.